Today, any of conventional surface-piercing type hydrofoil boats is equipped with a plurality of hydrofoils submergibly extended below the stem and the stern so that the boat can cruise itself at a high speed by way of decreasing hull resistance via proper function of hydrofoils for sustaining the hull lifted out of the water.
Nevertheless, according to the concept of such conventional surface-piercing type hydrofoil boat, since part of hydrofoils is extended above the water surface and constantly hit by waves while the boat cruises itself, so-called sea-worthiness remains poor, and in addition, since the hull itself cannot properly be stabilized against rolling effect generated by beam waves, cruising comfort cannot fully be provided.